1. Field of the Invention
The present invention relates to an automatic monitoring apparatus, and more particularly, to an automatic monitoring apparatus for automatically detecting a detection object, such as a suspicious person, based on the picture obtained from an image pickup device.
2. Description of the Related Art
In recent years, automatic monitoring apparatus have been developed wherein an intrusion of a suspicious person is automatically detected through monitoring of a picture input from a television camera, and upon detection of the intrusion, an alarm is given or the picture is recorded.
As such conventional apparatus, an automatic monitoring apparatus disclosed in Laid-Open Japanese Patent Publication (KOKAI) No. 4-273689, for example, is known. In this automatic monitoring apparatus, the path of movement and characteristic quantities (characteristic of shape, rate of change in shape) of a moving object are extracted from the picture signal obtained from a television camera and a background picture signal. If the path of movement of the moving object deviates from a normal area into a preset precautionary area or if one of the characteristic quantities exceeds a predetermined threshold, the moving object is judged to be a suspicious person, whereupon an alarm is given or a security guard is automatically notified of the picture of the object.
FIG. 10 is a plan view of a room in which bank's cash dispensers are installed. A normal area 101 where users of the cash dispensers normally move about and a precautionary area 102 where users normally do not enter are set beforehand. If the detected path 103 of movement of a person enters the precautionary area 102, the person is judged to be a suspicious person.
With the conventional automatic monitoring apparatus, however, it is difficult to detect a suspicious person with accuracy, giving rise to the problem that erroneous detection, such as detecting an innocent person as being suspicious, or conversely, failing to detect a true intruder, occurs with high frequency.
For example, let it be assumed that, as shown in FIG. 11, a television camera (not shown) is aimed at the upper part of a prison's wall 104 and that a precautionary area 105 is set within the picture obtained from the television camera. In this case, if a moving object 106 exists in the precautionary area 105, then it is judged to be a suspicious person. However, as shown in FIG. 12, it is probable that a bird 107 flies across the precautionary area 105, and also in such a case, the conventional apparatus judges the bird 107 a suspicious person.
Also, in the case where a road runs outside of the wall 104 and in the nighttime light from the headlights of an automobile impinges upon the wall 104, a problem arises in that the background illuminated with the light is detected as a moving object, though in actuality no moving object exists in the precautionary area 105.
Erroneous detection impairs the reliance on the automatic monitoring apparatus, and therefore, the frequency of erroneous detection should desirably be reduced as low as possible.
Further, when setting the precautionary area or thresholds used for comparison, a problem arises in that the acquisition, setting, and input of such values consume much labor.